Practical solutions to Submaximal Nordics

Practical solutions to Submaximal Nordics:insights for exercise familiarization and return totrain following knee flexors injury.Martin Buchheit 1, Ben M. Simpson 1 , Karim Hader 1 , and Mathieu Lacome 1

1Performance Department, Paris Saint Germain, Saint Germain En-laye, France

Hamstrings | Assesment | Strength | Rehabilitation

Headline

The Nordic exercise is probably the most controversial ex-ercise when it comes to training and testing knee flexors

(1). Among the various reasons for some practitioners to dis-like the Nordic exercise, the close-to-maximal intensity of theexercise is often advanced as a major limitation. In fact, theexercise requires high levels of strength to be performed cor-rectly (i.e., to manage to control the descent over the full rangeof knee extension). The existence of this so-called breakingpoint (2) during the descent likely prevents the strengtheningof the knee flexors over their full range of motion (i.e., to-ward full knee extension), where it may be in fact the mostbeneficial in relation to injuries (3). Also, weak and/or unfa-miliarized athletes also often report uncomfortable sensationsduring the exercise in relation to the high muscle tension. Fi-nally, because of the high levels of strength required to performthe exercise, the use of Nordics is also generally restricted tothe last phases of rehabilitation, which prevent both a pro-gressive loading and a continuous monitoring of athletes’ kneeflexors strength with the same exercise. For all the above-mentioned reasons, practical means that could allow athletesto perform submaximal Nordics (4, link) would likely increaseits player and staff buy-in, helping movement familiarizationand its integration at earlier stages during the return frominjuries process.

AimThe aim of the present study was to 1) (re)examine the fea-sibility of reducing Nordics intensity using elastic bands (4)and 2) quantify the magnitude of Force reduction in relationto band number and player’s body mass.

MethodsA group of 15 individuals (a mix of professional players andstaff (85 ± 10 kg)) from an elite soccer club performed 3 seriesof 2 reps of the Nordic exercise on a Nordbord (Vald Perfor-mance, Newstead, Queensland, Australia) using either 2 bands(Black Roll Resist Band, Grey band, Black Roll, Bottighofen,Switzerland), 1 band or none in a randomized order. Theband resistance is directly related to the stretch, with the re-sistance ranging from 40 to 80 kg when the band stretchesfrom 20 to 80% of its initial length (Black Roll unpublishedinformation). Players were requested to hold maximally theirdescend and complete the overall movement within approx.10 s. The overall set up is shown in Figure 1. The distancebetween the Nordbord and the wall ladder was 15 cm. Thebands were attached on the top of the wall ladder (2.35 mfrom the ground). All participants performed a standardizedwarm-up including 5 min of cycling at low intensity and dy-namic movements involving the posterior chain at high ampli-tude (lunge, full body squat and front kicks). Given the very

Fig. 1. A soccer player performing the Nordic exercise with 1 band.

Fig. 2. Individual Force traces during the Nordic exercise when using no band, 1

or 2 bands for an individual player (85 kg). Unit on the Y axis is N.

large relationship between Nordbord performance and bodymass (BM), Force data (both legs pooled) were allometricallyscaled based on the current sample distribution. The regres-sion equation of the Log-Log relationship was y = 1.34 x +0.0162, with r2 = 0.65, so the exponent used was 1.34 (5). Wefirst looked at the percentage of Force reduction as a functionof the number of bands used. Possible correlation between 1)

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Practical solutions to Submaximal Nordics

Fig. 3. Relationship between Nordbord Performance without bands and body

mass, suggesting the need for allomeric scalling to adjust for the likely effect of body

mass on performance. n = 15. See methods for details about the scalling procedure.

Fig. 4. Individual reduction (%) in Force applied to the Nordbord sensors when

using 1 or 2 bands. n = 15.

the % of Force reduction and BM, 2) the % of Force reductionand the band resistance in relation to BM and 3) the % ofForce reduction and scaled Nordbord performance were alsoexamined.

ResultsFigure 2 shows the typical Norbord Force measure during theNordic exercise while using no band, 1 or 2 bands in a represen-tative player. The very large relationship between Nordbordperformance and body mass is shown in Figure 3. Figure 4shows the individual % reduction of Force applied to the Forcecells as a function of the number of bands. In average, the re-duction was -15 ± 10 % and -40 ± 10 % for 1 and 2 bands,respectively. The % of Force reduction was not correlated withbody mass (Figure 5). Finally, there were large negative corre-lations between the % of Force reduction and scaled Nordbordperformance (Figure 6).

Fig. 5. Relationship between reduction in the Force applied to the Nordbord

sensors (%) when using 1 or 2 bands and body mass. n = 15.

Fig. 6. Relationship between reduction in the Force applied to the Nordbord

sensors (%) when using 1 or 2 bands and scaled Nordbord performance. n = 15.

DiscussionWe used here for first the time the changes in Nordbord perfor-mance in response to the use of commercially available bandsto assess practical means to alter Nordic exercise intensity.Our results show that within our specific setting (Figure 1),Nordic intensity can be reduced by 15 to 40 % using 1 and 2bands, respectively (Figure 4). It is important to note thatthe present results are specific to the present set up (type ofbands, placement and angle of the bands in relation to thebody, etc.) and can’t be directly extrapolated to other con-texts. We believe however that the overall approach is worthsharing for practitioners who may be able to develop their ownprotocols within their own context using their own materials.

Surprisingly, the results showed that body mass (Figure 5)had no impact on the % of Force reduction. While this may becounterintuitive a priori (i.e., the heavier the player, the lowerthe band effect), this confirms that other factors may explainboth the Nordbord performance (3, 6, 7) and the magnitudeof reduction in Force with bands. Among those, the ability toperform the movement over the full range of motion (or not)is probably the most important. While behind the scope ofthe present study, the break-point angle that is well related tooverall knee flexor strength and Nordic performance (2) mayneed to be considered to explain this point. In fact, Figure 6shows an inverse relationship between performance reductionwith bands (i.e., the greater the player’s strength, the greaterthe effect of the band(s)) and body-mass adjusted Nordbordperformance.

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Practical solutions to Submaximal Nordics

This could be interpreted as the following: in comparisonto their performance with the bands where they could likelycomplete the movement over the full range of motion (lowerload, no breaking-point), without bands (full body mass en-gaged) the weakest individual may not be able to control theeccentric movement until the last degrees of knee extension(presence of a breaking-point), leading to a lack of perfor-mance improvement despite their greater overall “mass” (5).Examining Force patterns in relation to motion characteris-tics (e.g., existence of a breaking point, knee angle of peaktorque. . . ) should therefore be the focus of future studies toclarify this latter hypothesis.

Key points• The Nordic exercise is controversial for many reasons – one

of them is related to the fact that it is an intense exercise es-pecially for weak players and/or those not familiarized withit, who can’t perform the full movement (full extension ofthe knees).

• We showed here that using simple commercially availablebands can help reduce the intensity by 15 (1 band) to 40(2 bands) %.

• Using bands may therefore be more effective than the tra-ditional version, at least until players build up enoughstrength to sufficiently control their body mass during theeccentric phase without the use of bands (4) (e.g., earlystages of rehabilitation following knee flexors injury).

• Whether submaximal Nordics performed over the completerange of motion have a greater potential for fascicle lengthimprovements (3, 8) in weak players and/or those showinga clear breaking point still needs to be examined.

• The large inter-individual differences in the response to theuse of the bands are unlikely related to athletes’ body massbut more likely to their typical (no band) Nordbord per-formance, with 1) the weakest benefiting more from theband assistance toward the full range of motion and 2) thestrongest showing a greater reduction in performance withbands.

AcknowledgementThe authors thank the staff D. Lefebre, M. Kramdi, C. Praud,G. Pasquer, D. Mantovani, J. Martin, B. Mazziotti and T.Bagot, and the players for their participation.

References1. Buchheit, M., et al., Injury rate and prevention in elitefootball: let us first search within our own hearts. Br J SportsMed, 2018.2. Sconce, E., et al., The validity of the nordic hamstring lowerfor a field-based assessment of eccentric hamstring strength. JSport Rehabil, 2015. 24(1): p. 13-20.3. Bourne, M.N., et al., An Evidence-Based Framework forStrengthening Exercises to Prevent Hamstring Injury. SportsMed, 2018. 48(2): p. 251-267.4. Contreras, B., The Nordic Ham Curl: A Staple Exercise forAthletes. https://bretcontreras.com/nordic-ham-curl-staple-exercise-athletes/. Bretcontreras.com, 2014(December, 16th).5. Buchheit, M., et al., The Effect of Body Mass on Ec-centric Knee-Flexor Strength Assessed With an InstrumentedNordic Hamstring Device (Nordbord) in Football Players. IntJ Sports Physiol Perform, 2016. 11(6): p. 721-726.6. Buchheit, M., et al., The quadrant of doom and hamstringinjuries: sexy but too easy? Sport Performance & ScienceReports, 2019. July(63): p. V1.7. Roe, M., et al., Eccentric knee flexor strength profilesof 341 elite male academy and senior Gaelic football players:Do body mass and previous hamstring injury impact perfor-mance? Phys Ther Sport, 2018.8. Lacome, M., et al., Knee-flexor eccentric training: Doestraining volume really matter? Int J Sports Physiol Perform,2019: p. Apr 29:1-27. doi: 10.1123/ijspp.2018-0947. [Epubahead of print].

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